1. Field of the Invention
The system of the invention is in the field of digital communication systems.
2. Description of the Prior Art
There are many systems in the art that effect transmission of digital signals from one electronic device to another electronic device. A general limitation of such systems is their inability to transmit over long distances at high signal rates without loss of signal fidelity.
Where transmission is effected between a computer and remote recorders such as typewriters or line printers, it is desirable to include a construction such that the computer senses whether or not the recorder is in service at the time that the information is to be transmitted to it. Otherwise, there can be a complete loss of data output from the computer. Although transmission systems do exist where recorders furnish signals to indicate that they are in service and capable of receiving signals transmitted to them, such systems are generally of the audio-frequency modulation type or of the current-loop type. The audio-frequency modulation type requires special coder-decoder devices at the computer and recorder and usually is limited to relatively slow signal transmission rates. The current-loop type is limited to the relatively short distances permitted by acceptable transmission line resistance.